To keep a movable clincher closed without needing any special parts.

An operating mechanism of a movable clincher consists of an operating member 9 which is arranged on a base member 1 and provided in a movable manner at a first position to close a movable clincher 6 and a second position to open the movable clincher 6, and a link mechanism to move the operating member 9 from the second position to the first position in an interlocking manner with the downward movement of an operation handle 3. When a frame member 2 is in the upper position, the link mechanism is at the position to move the operating member 9 to the first position side. When the frame member 2 is moved downward, the link mechanism is at the position to allow the operating member 9 to be moved to the second position side.